According to a study conducted by CESI Debt Solutions, 80% of married people hide purchases from their mates. In a random sample of 20 married people, find and interpret:
(a) The probability exactly 15 hide purchases from their mates.
(b) The probability at least 19 hide purchases from their mates.
(c) The probability fewer than 19 hide purchases from their mates.
(d) The probability between 15 and 17, inclusive, hide purchases from their mates.